e-Journal of Dentistry Oct - Dec 2012 Vol 2 Issue 4 240 O riginal Article www.ejournalofdentistry.com ABSTRACT Objectives: This study analyzed postero-anterior (PA) cephalometric radiographs to investigate the association between untreated dental crossbites and facial skeletal asymmetry in orthodontic patients. Materials and Methods: Sixty subjects, 14 years and older, were randomly selected from the SUNY Buffalo orthodontic clinic’s patient records and divided equally as a control or experimental group. Experimental group subjects were required to have a minimum of two posterior teeth in crossbite and to have a skeletal posterior crossbite tendency as determined from the Ricketts PA cephalometric analysis (a J-J to Ag-Ag ratio of <0.75). The control group had Class I malocclusion without a dental crossbite and transverse skeletal discrepancy as measured according to the PA Ricketts skeletal analysis. Craniofacial symmetry was determined for all of the subjects by means of reference lines constructed on the PA radiographs. Results: The observed differences between the ratios (JR-JL/RAG-LAG) of the control and test groups were statistically significant (F = 113.624, df = 1, 56, p < 0.001). There were no significant indications (p > 0.05) of facial asymmetry recorded for both groups. Conclusion: The present study is in agreement with previous studies that found no link between posterior crossbite malocclusion and asymmetrical growth. Key Words: Orthodontics, Oral diagnosis, Morphometrics, Anatomy, Occlusion. S KELET AL A S YMMETRY E VA LUATI ON I N P A TI E NT S WI TH P OS TE RI OR CROSSBI TES Nancy Kate Pancko 1 , T.S Al-Jewair 2 , S. T abbaa 3 , C. B. Preston 4 1 Na ncy Ka te Pa ncko, DDS, MS, Orthodont i st, Pr i va te pr act i ce, USA. 2 Thi kr i a t Al -J ewa i r, BDS, MBA, MSc, FRCD(C), Cli ni ca l Ins tructor, Orthodont i c Dep artment, St a te Uni versi ty of New Yor k a t Buff a l o 3 Sa wsa n Ta bbaa , DDS, MS, Assi st a nt Pro f essor, Orthodont i c Depa rtment, St a te Uni versi ty of New Y or k a t Buff a l o 4 C. Br i a n Pres ton, BDS, PhD, Prof essor a nd Cha i r, Orthodont i c Department, St a te Uni versi ty of New Y or k a t Buff a l o Correspondence: Thi kr i a t Al -Jewa i r; 140 Squi re Ha ll , School of Dent a l Medici ne, SUNY Buff a l o USA. Ema il : t a l j ewa i r@gma il.com Recei ved Oct 10, 2012; Revi sed Nov 23, 2012; Acc epted Dec 28, 2012 INTRODUCTION Uncorrected posterior dental crossbites have been implicated as being an etiologic factor that could contribute to asymmetries that have been observed in components of the craniofacial skeleton (2). Posteroanterior (PA) cephalograms are valuable in assessing the role that the jaws play in the development of crossbites (2, 3) . At least three methods have been used to assess facial asymmetry in a qualitative and quantitative manner from PA cephalograms (4) . These methods use reference lines and they represent the anatomic, the bisection, and the triangulation approaches to determining facial symmetry. The anatomic approach uses a midsagittal plane that passes through the crista gali and that is perpendicular to a horizontal line connecting the bilateral zygomatico- frontal sutures. The perpendicular distances from bilateral anatomic landmarks can be compared to provide a measure of the facial skeletal symmetry that is present in a particular skull (4) . The bisection approach to finding the midline of a face may be used when the crista gali or the zygomatico- frontal sutures are difficult to identify. According to this method multiple bilateral landmarks are identified and horizontal lines, with their midpoints determined, are then constructed to connect the respective landmarks. A facial sagittal midline is constructed by drawing a reference line perpendicular to the true horizontal line and by having this line pass through as many of the midpoints of the bilateral landmarks as possible (4) . The triangulation approach to measuring facial symmetry divides the face into a series of bilateral triangles based on the facial midline and a number of bilateral landmarks. The bilateral triangles are then compared to obtain insight into the symmetry of the face being studied (5) . The results of previous studies that attempted to show there is an association between posterior dental crossbites and craniofacial skeletal asymmetry were largely inconclusive (6, 7). Therefore, this study was undertaken to determine whether patients with untreated dental crossbites in combination with relatively narrow maxillae, also have features of craniofacial skeletal asymmetry.